Steering mechanism for an appliance having directional wheels and drawn by a tractor or the like to which it is attached by a three or four point linkage

ABSTRACT

Steering mechanism for a tractor-drawn appliance having directional wheels and connected to the tractor by a three- or four-point linkage. The mechanism has a steering shaft pivotally connected to the rear end of the tractor and to the appliance chassis. Steering members are connected both to the steering shaft and to the directional wheels. On lateral displacement of the steering shaft with reference to the direction of travel of the tractor, the directional wheels are deflected in the same sense.

United States Patent Inventor Appl. No. Filed Patented Priority Arnold Gego 67 Soerser Weg, Aachen, Germany 781,103

Dec. 4, 1968 Feb. 9, 1971 Dec. 8, 1967 Germany A STEERING MECHANISM FOR AN APPLIANCE HAVING DIRECTIONAL WHEELS AND DRAWN BY A TRACTOR OR THE LIKE TO WHICH IT IS ATTACHED BY A THREE OR FOUR POINT LINKAGE 14 Claims, 6 Drawing Figs.

Int. Cl B62d 53/00 Field of Search 280/442- 34 3| 5% ss 2 3o 22 [56] References Cited UNITED STATES PATENTS 2,691,931 10/1954 Wilson 172/439X 2,713,296 7/1955 Silver et a1. 172/284 2,780,161 2/1957 Frevik et a1 172/285 3,3 24,956 6/1967 Ritchie l72/439X 3,424,476 l/1969 Greyling 280/443 OTHER REFERENCES German printed application No. 1,166,541 published March 26, 1964 to Wagner and Reinhold Primary ExaminerLe0 Friaglia AttorneyMason, Fenwick & Lawrence ABSTRACT: Steering mechanism for a tractor-drawn appliance having directional wheels and connected to the tractor by a threeor four-point linkage. The mechanism has a steering shaft pivotally connected to the rear end of the tractor and to the appliance chassis. Steering members are connected both to the steering shaft and to the directional wheels. On lateral displacement of the steering shaft with reference to the direction of travel of the tractor, the directional wheels are deflected in the same sense.

- PATENTEUFEB 9m: 3561.791

SHEET 2 [IF 4 INVENTOR ARNOLD (Redo ATTORNEYS pmm nrm 9mm 3561.791

' SHEET 3 OF 4 INVENTOR ARNOLD G500 BY mamgmfiwmci ATTORNEY PATENTED E8 9 I97] saw u 0F 4 INVENTOR ARNOLD GEGO QJ-LHXMQ/ ATTORNEYS STEERING MECHANISM FOR AN APPLIANCE HAVING DIRECTIONAL WHEELS AND DRAWN BY A TRACTOR OR THE LIKE TO WHICH IT IS ATTACHED BY A THREE OR FOUR POINT LINKAGE FIELD OF THE INVENTION This invention relates to a steering mechanism for an appliance drawn by a tractor or the like and connected thereto by means of a three-or four-point linkage and having directional wheels.

Tractor drawn appliances, connected by a three or four point linkage and having directional wheels, are used in various fields, and particularly in agriculture and include inter alia sowing, hoeing, spraying and thinning appliances or machines.

DESCRIPTION OF THE PRIOR ART In an appliance drawn by a tractor, connected thereto by a three or four point linkage and particularly in use thereof in agriculture, it is necessary that the appliance should follow the tractor centrally. This object is achieved in known appliances with the aid of the directional wheels, which also act, in many instances, as the supporting wheels thereof. In the known arrangements the directional wheels are usually operated by means of the steering wheel by a separate operator sitting on the appliance. There are also other known means for operating the directional wheels. In these cases too an operator is required for operating the directional wheels.

An object of the invention is to provide a steering mechanism which will effect automatic steering of the appliance and which is simple, reliable and rugged in construction and operation.

SUMMARY OF THE INVENTION According to this invention there. is provided a steering mechanism for an appliance having directional wheels and drawn by a tractor or the like to which it is attached by a three or four point linkage, comprising a steering shaft pivotally connected to the rear end of the tractor or the like and to the appliance chassis, and steering members connected on the one hand to the steering shaft and on the other hand to the directional wheels such that on lateral displacement of the steering shaft with reference to the direction of travel of the tractor or the like, the directional wheels are deflected in the same sense.

With this construction of steering mechanism an appliance drawn by a tractor is thus automatically caused to follow the tractor in alignment, Should the appliance move sideways the steering shaft performs a corresponding lateral movement with reference to the direction of travel of the tractor and this lateral deflection of the steering shaft in turn effects through the steering members a similar deflection of the directional wheels. Due to this deflection of the directional wheels of the appliance the latter is returned to the position of alignment behind the tractor.

The steering shaft is preferably constructed of a number of telescopic parts and capable of being pivoted in all directions. Consequently, the steering shaft can follow every movement performed by the appliance and can be deflected laterally and moved up and down.

The steering members may comprise steering levers secured to the directional wheels and a track rod connecting the members the track rod being connected to the steering shaft in motion transmitting manner. This arrangement has the advantage of being particularly simple, and it has the advantage that steering levers and track rods already existing in the appliance can be used.

Various arrangements within the scope of the invention are possible. In one construction the track rod is disposed behind the point of connection between the steering shaft and the appliance chassis and is connected to a part of the steering shaft extending rearwardly beyond this point of connection. In the other construction the track rod is in front of the point of connection between the steering shaft and the appliance chassis,

the track rod being connected to a part of the steering shaft situated in front of this point of connection. Which of these two forms is to be used depends on the nature of the appliance.

The steering members may be formed by a steering axle which is rigidly connected to the rear part of the steering shaft, is disposed at right angles thereto and carries the directional wheels at its ends. In this arrangement the steering axle is preferably disposed in the vertical plane of the connecting point between the steering shaft and the appliance chassis. The steering shaft, the steering axle connected thereto and the directional wheels provided at the ends thereof form a steering bogie for the appliance.

In another arrangement according to the invention there may be used as steering member for a directional wheel a hydraulic operating cylinder, which acts upon a steering lever fixed to the directional wheel and is under the influence of a hydraulic control slide displaceable by means of the steering shaft. This arrangement is suitable primarily for steering a comparatively large and heavy appliance which requires fairly large forces for its steering.

The control slide in its central position connects two conduits leading to the two ends of the cylinder and on being moved from its central position connects these two conduits either to a supply pipe from a pressure fluid pump or to a return pipe leading to a fluid tank. As a result, the directional wheels are not operated when the control slide is in its central position, which is the case when the appliance follows the tractor in alignment. On the other hand, the directional wheels will be deflected in one direction or the other when the control slide is moved from its central position, which always occurs when the appliance moves sideways with reference to the tractor.

For displacing the control slide by means of the steering shaft, the control slide may be connected to the steering shaft for mutual movement. This manner of connecting the control slide to the steering shaft is particularly simple.

In a connection of the control slide with the steering shaft for interrelated movement the invention may further provide that this connection shall include a transmission lever. By use of such a transmission lever a particularly large response sensitivity of the control slide to lateral displacement of the steering shaft is achieved, this being of considerable advantage.

The control slide may be slidably mounted on the piston rod of the cylinder and the control slide may be connected to the steering shaft by a lever linkage pivotally mounted on the appliance chassis. In this arrangement the linkage, the control slide and the cylinder provide a connection for interrelated movement between the steering shaft and the steering lever of the directional wheel. Moreover, servo steering of the directional wheel is brought about by the cylinder and its control slide.

As a steering member for each additional directional wheel a further operating cylinder may be provided which acts upon a steering lever secured to this directional wheel and is subject to the influence of the same control slide.

Preferably, however, each additional directional wheel is provided with a further steering lever, and these further steering levers being connected by a track rod to that steering lever which is in engagement with the operating cylinder.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will now be described in more detail by way of example, with reference to the accompanying drawings in which:

FIG. I shows diagrammatically a tractor and an appliance drawn thereby with a first embodiment of the steering mechanism, partly in side elevation and partly in longitudinal section;

FIG. 2 shows diagrammatically a directional wheel and parts of the appliance shown in FIG. 1 in side elevation;

FIG. 3 is a diagrammatic top plan of the tractor, the appliance and the steering mechanism of FIG. I;

FIG. 4 is a diagrammatic top plan of a tractor and an appliance with a modification of the first embodiment of steering mechanism;

FIG. 5 is a diagrammatic top plan of a tractor and an appliance with a second embodiment of steering mechanism; and

FIG. 6 is a diagrammatic top plan of a tractor and an appliance with a third embodiment of steering mechanism.

DESCRIPTION OF EMBODIMENTS In all FIGS. the tractor is indicated at S and the appliance drawn thereby at G. The tractor shown is of the usual design. Apart from their steering mechanisms the appliances G drawn by the tractors S are also of usual design.

The appliance G is in each case connected to its tractors S by a three point linkage comprising linkage arms l1, 12, 13, their forward ends being pivotally connected to the tractors S and their rear ends being hinged to the chassis 14 of the appliances G. The connection of an appliance G to a tractor S by the three point linkage I1, 12, [3 permits lateral movement of the appliance G with reference to the tractor S. Apart from this, the three point linkage ll, 12, 13 enables the appliance G to be lifted off the ground and lowered on to it.

The appliances G may serve different purposes. For this re ason the appliances G are represented diagrammatically. FIG. I shows an appliance with harrowing tools 15, while FIG. 6 illustrates an appliance G which is provided with a sowing device 17 and a furrowing tool 18.

All the appliances shown are equipped with directional wheels 19. These directional wheels 19 serve, on the one hand, to steer the appliances G and on the other hand to support them on the ground. In order that the directional wheels 19 may stand up to lateral forces, which is of importance when the appliances are towed on a slope as well as in steering them, they are provided on their circumference with a central rim 20.

The construction and the arrangement of the directional wheel 19 of an appliance G is illustrated in more detail in FIG. 2. The directional wheel 19 is arranged as a trailing directional wheel and is mounted in a correspondingly rearwardly extending wheel fork 21. The wheel fork 21 is mounted rotatably about a vertical axis and is adjustable up and down in the direction of this axis in a bearing sleeve 22, which in turn is secured to the chassis 14 of the appliance. For vertical adjustment of the wheel fork 21 and wheel 19 an adjusting spindle 23 extending into the bearing sleeve 22 is provided.

All embodiments of the steering mechanism are provided with a steering shaft 24, which is pivotally connected to the rear end of the tractor S, as well as to the chassis 14 of the appliance G. In all embodiments of the steering mechanism the,

steering shaft 24 has a front part 25 which, by means of pivot members 26, is pivotally connected to connecting parts 27 of the tractor S. Furthermore, the steering shaft 24 has a middle part 28 which is telescopically connected to the front part 25. With this telescopic connection the length of the steering shaft 24 can be varied.

In the embodiment of the steering mechanism according to FIGS. 1 and 3 rearwardly extending steering levers 29 are secured to the wheel forks 21. The rear ends of these steering levers 29 are pivotally connected to a track rod 30. Further, the steering shaft 24 has a rear part 31. The rear part 31 of the steering shaft 24 is connected to the middle part 2% thereof by means of a pivot 32, which permits relative movement thereof in the vertical direction, but not laterally. The rear part 31 of the steering shaft 24 is pivotally connected to the chassis M of the appliance by means of a vertical pin 33. Also the rear end of the rear part 31 of the steering shaft 24 is pivotally connected to the track rod 30. For this purpose, at the said rear end is a vertical longitudinal slot 34 and a central pivot pin 35 on the track rod 30, the slot and pin being in pivotal engagement.

Should a lateral movement arise for any reason in the appliance G shown in FIGS. 1 and 3 with reference to the tractor S, a corresponding lateral displacement of the steering shaft 24 will occur simultaneously. The deflection of the steering shaft 24 causes in turn, through the track rod 30 and the steering levers 29, deflectionof the directional wheels 19 in the same sense. As a result the appliance G is steered back to its aligned position behind the tractor S by the directional wheels 19.

The steering mechanism shown in FIG. 4 corresponds in principle to the steering mechanism according to FIGS. 1 and 3. However, in this steering mechanism the steering levers 36 connected to the wheel forks 21 extend forwardly. Moreover.

this steering mechanism has a track rod 37 which is pivotally connected to the front end of the steering levers 36. The steering shaft 24 of this steering mechanism also has a rear part 31 which, in the same manner as in the steering mechanism shown in FIGS. 1 to 3, is connected by means of a pivot 32 to the middle portion 28 of the steering shaft 24. The rear part 31 of the steering shaft 24 is, however, in this steering mechanism, connected with its rear end by means of a vertical pivot pin 38 to the chassis 14 of the appliance G. The track rod 37 is connected by a vertical pivot pin 39 to the rear part 31 of the steering shaft 24 at a point located in front of the point of connection of this part and the chassis 14 of the appliance G. The operation of the steering mechanism just described corresponds to that of FIGS. 1 and 3.

In the embodiment shown in FIG. 5 the steering elements are constituted by a steering axle 40 mounted so as to be rockable in a horizontal plane about a vertical pivot pin 42 fixed to a bracket 41 of the chassis 14 of the appliance G. A directional wheel 19 is provided at each end of the steering axle 40. g

In this steering mechanism the steering shaft 24 has a rear part 43 formed by two struts 43a, 43b, universally jointed by a ball joint 44 to the middle part 28 of the steering shaft 24 so as to be movable in all directions. In addition, the struts 43a. 4312 are rigidly connected to the steering axle 40, which thus provides a pivotal connection between the steering shaft 24 and the chassis 14 of the appliance C.

Unlike the steering mechanism according to FIGS. I to 4, in the steering mechanism of FIG. 5 the front part 25 of the steering shaft 24 is connected to the rear end of the tractor S by a pivot 26 and connecting parts 27 so as to be movable up and down only, and not laterally. As a result, when the applianceG moves laterally with reference to the tractor S only a corresponding lateral movement of the rear part 43 of the steering shaft 24 takes place. However, the lateral deflection of the rear part 43 of the steering shaft 24 causes an angular movement in the same sense of the steering axle 40 and thus of the directional wheels 19. Consequently the appliance G is steered back into its aligned position behind the tractor S by the directional wheels 19.

In the steering mechanism shown in FIG. 6 the appliance G drawn by the tractor S also has two directional wheels 19. Connected to the wheel forks 21 of these directional wheels 19 are rearwardly extending steering levers 45. Pivoted to the rear ends of the steering levers 45 is a track rod 46 connecting them together. In this steering mechanism the operation of the directional wheels 19 is controlled by a hydraulic operating cylinder 47 pivoted to a bracket 48 of the chassis 14 of the appliance. Further for this purpose the piston rod 49 of the piston 50 of the cylinder 47 is pivotally connected to a steering lever 45, and the steering shaft 24 is connected to the chassis 14 by a ball joint and supporting struts 52, 53.

On the piston rod 49 a control slide 54 is longitudinally slidable. From the control slide 54 a pressure fluid conduit 55 leads to one end and a pressure fluid conduit 56 to the other end, of the casing 57 of the operating cylinder 47. Furthermore, two conduits 58, 59 are connected to the control slide 54. Of these two conduits the conduit 58 is a fluid feed pipe connected to a fluid pump (not shown) while the conduit 59 is a fluid return pipe leading to a fluid tank (not shown).

The control slide is capable of taking up a middle position as well as lateral positions. In its middle position it interconnects the feed pipe 58 and the return pipe 59, and also interconnects the conduits 55 and 56. In one of the lateral positions of the control slide 54 (indicated by parallel arrows) it interconnects the conduit 55 with the feed pipe 58 and the conduit 56 with the return pipe 59. In the other lateral position of the control slide (indicated by intersecting arrows) the conduit 56 is connected to the feed pipe 58 and the conduit 55 is connected to the return pipe 59,

The control slide 54 is connected by a pivotal linkage system 60, 61, 62 to the middle part 28 of the steering shaft 24. The pivotal linkage system has a two-armed lever 60 pivotally mounted on a bearing element 63 of the chassis 14. The forward end of the two-armed lever 60 is pivotally connected to one lever 6l which, in turn, is pivotally connected to the middle part 28 of the steering'shaft 24. Another lever 62 is pivotally connected to the rear end of the two-armed lever 60. This lever 62 is, in turn, pivotally connected to an arm 64 fixed to the casing of the control slide 54.

Should the appliance G move sideways with reference to the tractor S, then due to the resultant lateral displacement of the steering shaft, the control slide 54 is displaced on the piston rod 49 through the intermediary of the lever linkage 60, 61, 62. Through the lever linkage 60, 61, 62 and more particularly due to the offside mounting of the two armed-lever 60 on the bearing element 63 variation of leverage of the lateral displacement of the steering shaft 24 upon the control slide 54 takes place. As a result the control slide 54 has increased sensitivity of response.

As a result of displacement of the control slide 54 this is moved from its midposition to that one of its lateral positions which charges the operating cylinder 47 with pressure fluid so that its piston 50 and piston rod 49 move in sympathy with the control slide 54. This causes the steering levers 45 and therewith the directional wheels l9 to move sideways corresponding to the inclined position of the steering shaft 24. Due to the sideways movement of the directional wheels 19 the appliance G is then steered back into its aligned position behind the tractor S. This causes the steering shaft 24 to swing back into its midposition too and thus the control slide 54 is also returned to its initial position by the action of the lever linkage system 60, 61, 62. The piston rod 49 and the piston 50 follow the control slide 54in the corresponding direction and take with them, through the steering levers 45 and the track rod 46, the directional wheels 19. When the steering shaft 24, the control slide 54 and the piston 50 have reached their middle or initial position, no further pressure fluid is charged into the operating cylinder 47 and the directional wheels 19 are again located in their normal midposition.

I claim:

1. Steering mechanism for an appliance having directional wheels and drawn by a tractor to which it is pivotally attached by a three point linkage, comprising a steering shaft pivotally connected to the rear end of the tractor and to the appliance chassis, and steering members connected on the one hand to the steering shaft and on the other hand to the directional wheels such that on lateral displacement of the steering shaft with reference to the direction of travel of the tractor, the directional wheels are deflected in the same sense.

2. Steering mechanism according to claim 1, wherein the steering shaft is constructed of a number of telescopic parts and capable of being pivoted in all directions.

3. Steering mechanism according to claim 1, wherein steering levers are secured to the directional wheels with an interconnecting track rod, the track rod being connected to the steering shaft in motion transmitting manner.

4. Steering mechanism according to claim 3, wherein the track rod is disposed behind the point of connection of the steering shaft and the appliance chassis, the track rod being connected to a part of the steering shaft extending rearwardly beyond such point of connection' 5. Steering mechanism according to claim 3, wherein the track rod is disposed in front of the point of connection between the steen'n shaft and the appliance chassis, the track rod being connecte to a part of the steering shaft situated in front of such point of connection.

6. Steering mechanism according to claim 1 wherein the steering members comprise a steering axle rigidly connected to the rear part of the steering shaft and disposed at right angles thereto and carrying directional wheels at its ends.

7. Steering mechanism according to claim 6, wherein the steering axle is disposed in the vertical plane of the point of connection between the steering shaft and the appliance chas- SIS.

8. Steering mechanism according to claim 1, having a hydraulic operating cylinder for steering a directional wheel, which cylinder acts upon a steering lever secured to the directional wheel and is subject to the action of a hydraulic control slide which is displaced together with the steering shaft and thereby causes a deflection of the steering wheel in the same sense.

9. Steering mechanism according to claim 8, wherein control slide, in its midposition, connects two conduits leading to the ends of the operating cylinder, and on being moved from its midposition, connects the said two conduits either with a pipe from a pump for a pressure fluid or with a return pipe leading to a fluid tank.

10. Steering mechanism according to claim 8, wherein the control slide is connected to the steering shaft in motion-transmitting manner.

11. Steering mechanism according to claim 8, wherein the control slide is connected to the steering shaft through a transmission lever.

l2. Steering mechanism accordingto claim 8, wherein the control slide is mounted slidably on the piston rod of the operating cylinder, and the control slide is connected to the steering shaft by a pivotal lever linkage system.

13. Steering mechanism according to claim 8 wherein certain directional wheels include a further hydraulic operating cylinder acting upon a directional lever secured to the said certain wheels, which further cylinder is subject to the action of the said control slide.

14. Steering mechanism according to claim 8 wherein certain directional wheels include a further steering lever, the said further levers being connected for interrelated movement by a track rod to that steering lever which is connected to the operating cylinder. 

1. Steering mechanism for an appliance having directional wheels and drawn by a tractor to which it is pivotally attached by a three point linkage, comprising a steering shaft pivotally connected to the rear end of the tractor and to the appliance chassis, and steering members connected on the one hand to the steering shaft and on the other hand to the directional wheels such that on lateral displacement of the steering shaft with reference to the direction of travel of the tractor, the directional wheels are deflected in the same sense.
 2. Steering mechanism according to claim 1, wherein the steering shaft is constructed of a number of telescopic parts and capable of being pivoted in all directions.
 3. Steering mechanism according to claim 1, wherein steering levers are secured to the directional wheels with an interconnecting track rod, the track rod being connected to the steering shaft in motion transmitting manner.
 4. Steering mechanism according to claim 3, wherein the track rod is disposed behind the point of connection of the steering shaft and the appliance chassis, the track rod being connected to a part of the steering shaft extending rearwardly beyond such point of connection.
 5. Steering mechanism according to claim 3, wherein the track rod is disposed in front of the point of connection between the steering shaft and the appliance chassis, the track rod being connected to a part of the steering shaft situated in front of such point of connection.
 6. Steering mechanism according to claim 1 wherein the steering members comprise a steering axle rigidly connected to the rear part of the steering shaft and disposed at right angles thereto and carrying directional wheels at its ends.
 7. Steering mechanism according to claim 6, wherein the steering axle is disposed in the vertical plane of the point of connection between the steering shaft and the appliance chassis.
 8. Steering mechanism according to claim 1, having a hydraulic operating cylinder for steering a directional wheel, which cylinder acts upon a steering lever secured to the directional wheel and is subject to the action of a hydraulic control slide which is displaced together with the steering shaft and thereby causes a deflection of the steering wheel in the same sense.
 9. Steering mechanism according to claim 8, wherein control slide, in its midposition, connects two conduits leading to the ends of the operating cylinder, and on being moved from its midposition, connects the said two conduits either with a pipe from a pump for a pressure fluid or with a return pipe leading to a fluid tank.
 10. Steering mechanism according to claim 8, wherein the control slide is connected to the steering shaft in motion-transmitting manner.
 11. Steering mechanism according to claim 8, wherein the control slide is connected to the steering shaft through a transmission lever.
 12. Steering mechanism according to claim 8, wherein the control slide is mounted slidably on the piston rod of the operating cylinder, and the control slide is connected to the steering shaft by a pivotal lever linkage system.
 13. Steering mechanism according to claim 8 wherein certain directional wheels include a further hydraulic operating cylinder acting upon a directional lever secured to the said certain wheels, which further cylinder is subject to the action of the said control slide.
 14. Steering mechanism according to claim 8 wherein certain directional wheels include a further steering lever, the said further levers being connected for interrelated movement by a track rod to that steering lever which is connectEd to the operating cylinder. 